Our age struggles to understand what’s going on with religion. The 21st century will either be religious or it won’t be… But what do we know about religion? Sociology was founded on the ambition to reveal what had been going on for thirty centuries, in order to liberate man from it. But modernity has neither confirmed its prediction nor lived up to its expectations. The great political and national ideologies, those veritable civil religions, have been experiments in baroque and misguided religiosity. How can we understand them when the disappearance of religion was predicted? This book takes stock of what the main thinkers of modernity – Durkheim, Marx, Weber – have taught us about religion. But also the impasses of their conception. Their search for a political causality in religion may have led them to miss its exact meaning. It’s not the least bit surprising that they inscribed a principle of transcendence in their rather materialistic doctrine. This paradox is the common thread that helps us understand the debate on reality that divides contemporary thought.